Non-Lorentzian spectral diffusion line shapes in glasses: Analysis based on the two-level-system model

2002 ◽  
Vol 116 (12) ◽  
pp. 5107 ◽  
Author(s):  
B. M. Kharlamov ◽  
G. Zumofen
Keyword(s):  
Spectral Diffusion ◽  
System Model ◽  
Level System ◽  
Line Shapes

Coherence preservation in 3-level atom

2011 ◽  
Vol 11 (5&6) ◽  
pp. 420-433
Author(s):  
Fei Yang ◽  
Shuang Cong
Keyword(s):  
Ground State ◽  
Numerical Experiments ◽  
Control Object ◽  
System Model ◽  
Level System ◽  
Multilevel System ◽  
Control Field ◽  
Object A ◽  
Breakdown Time ◽  
Level Atom

Coherence preservation of a multilevel system subject to Markovian decoherence is studied. A Lambda-type three-level atom is selected as the system model. Coherence preservation between a ground state and the excited state of such a system is defined as the control object. A control field is designed by means of constraining the constant coherence condition. For the singularities of the control field, we qualitatively analyze the breakdown time, i.e. the time of control diverging. We obtain the region in which the state stays to maintain coherence forever in the case that the three-level system is reduced to a two-level one. For other cases, we investigate how different parameters affect the breakdown time qualitatively. Numerical experiments are implemented on a three-level quantum system and the experimental results are analyzed.

scholarly journals ISSM-SLPS: geodetically compliant Sea-Level Projection System for the Ice-sheet and Sea-level System Model v4.17

2020 ◽  
Vol 13 (10) ◽  
pp. 4925-4941
Author(s):  
Eric Larour ◽  
Lambert Caron ◽  
Mathieu Morlighem ◽  
Surendra Adhikari ◽  
Thomas Frederikse ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ocean Circulation ◽  
Ice Sheets ◽  
Ice Sheet ◽  
System Model ◽  
Level System ◽  
Projection System ◽  
Forward Models ◽  
And Sea Level

Abstract. Understanding future impacts of sea-level rise at the local level is important for mitigating its effects. In particular, quantifying the range of sea-level rise outcomes in a probabilistic way enables coastal planners to better adapt strategies, depending on cost, timing and risk tolerance. For a time horizon of 100 years, frameworks have been developed that provide such projections by relying on sea-level fingerprints where contributions from different processes are sampled at each individual time step and summed up to create probability distributions of sea-level rise for each desired location. While advantageous, this method does not readily allow for including new physics developed in forward models of each component. For example, couplings and feedbacks between ice sheets, ocean circulation and solid-Earth uplift cannot easily be represented in such frameworks. Indeed, the main impediment to inclusion of more forward model physics in probabilistic sea-level frameworks is the availability of dynamically computed sea-level fingerprints that can be directly linked to local mass changes. Here, we demonstrate such an approach within the Ice-sheet and Sea-level System Model (ISSM), where we develop a probabilistic framework that can readily be coupled to forward process models such as those for ice sheets, glacial isostatic adjustment, hydrology and ocean circulation, among others. Through large-scale uncertainty quantification, we demonstrate how this approach enables inclusion of incremental improvements in all forward models and provides fidelity to time-correlated processes. The projection system may readily process input and output quantities that are geodetically consistent with space and terrestrial measurement systems. The approach can also account for numerous improvements in our understanding of sea-level processes.

Control Simulation for Three Tank Water Level

2014 ◽  
Vol 513-517 ◽  
pp. 3053-3056
Author(s):  
Le Peng Song ◽  
Di Jian Xu ◽  
Jin Liang Shi ◽  
Bi Jia
Keyword(s):  
Linear Relationship ◽  
Water Level ◽  
Experimental System ◽  
System Model ◽  
Level System ◽  
Level Control ◽  
Third Order ◽  
Object Of Study ◽  
Tank Water ◽  
Tank Level

Three-tank liquid level system of its vessels belonging to non-linear relationship between the coupling. In this paper, three tank level control experimental system as the research object, the establishment of the level system model, and according to the experimental requirements: upper, middle tank to stabilize the value of the lower tank eventually reaches a given value, forming a typical third-order object of study.

scholarly journals Extended enthalpy formulations in the Ice-sheet and Sea-level System Model (ISSM) version 4.17: discontinuous conductivity and anisotropic streamline upwind Petrov–Galerkin (SUPG) method

2020 ◽  
Vol 13 (9) ◽  
pp. 4491-4501
Author(s):  
Martin Rückamp ◽  
Angelika Humbert ◽  
Thomas Kleiner ◽  
Mathieu Morlighem ◽  
Helene Seroussi
Keyword(s):  
Sea Level ◽  
Geometric Mean ◽  
Ice Sheet ◽  
System Model ◽  
Level System ◽  
Aspect Ratios ◽  
3D Elements ◽  
Supg Method ◽  
Ice Sheet Modelling ◽  
And Sea Level

Abstract. The thermal state of an ice sheet is an important control on its past and future evolution. Some parts of the ice sheet may be polythermal, leading to discontinuous properties at the cold–temperate transition surface (CTS). These discontinuities require a careful treatment in ice sheet models (ISMs). Additionally, the highly anisotropic geometry of the 3D elements in ice sheet modelling poses a problem for stabilization approaches in advection-dominated problems. Here, we present extended enthalpy formulations within the finite-element Ice-Sheet and Sea-Level System model (ISSM) that show a better performance than earlier implementations. In a first polythermal-slab experiment, we found that the treatment of the discontinuous conductivities at the CTS with a geometric mean produces more accurate results compared to the arithmetic or harmonic mean. This improvement is particularly efficient when applied to coarse vertical resolutions. In a second ice dome experiment, we find that the numerical solution is sensitive to the choice of stabilization parameters in the well-established streamline upwind Petrov–Galerkin (SUPG) method. As standard literature values for the SUPG stabilization parameter do not account for the highly anisotropic geometry of the 3D elements in ice sheet modelling, we propose a novel anisotropic SUPG (ASUPG) formulation. This formulation circumvents the problem of high aspect ratio by treating the horizontal and vertical directions separately in the stabilization coefficients. The ASUPG method provides accurate results for the thermodynamic equation on geometries with very small aspect ratios like ice sheets.

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